| The main characteristics of heavy oil is high viscosity,containing large amount of high molecular compound such as colloid and asphaltene,The seepage flow of heavy oil does not comply with the Darcy law.At present,the studies about the seepage law of heavy oil are mainly in theory but little in laboratory.On the basis of predecessors' research,this paper make more studies in the non-linear flow and relative permeability calculation method of heavy oil reservoir,through a large number of experiments and theoretical analysis.Firstly,by studying the rheological characteristics of different types of heavy oil under different temperature,this paper reveals the rheological model of different types of heavy oil,and the mechanism of nonlinear seepage characteristics of heavy oil.On this basis,the threshold pressure and the relationships of velocity-pressure gradient under irreducible water saturation was studied.The empirical regularity of threshold pressure gradient,the parameters describing the velocity-pressure gradient curve with gas permeability and fluid viscosity was established based on a lot of experimental data regression.And the characteristics of threshold pressure and the description method of single flowing of heavy oil was also obtained.Because of the complexity of the multiphase seepage flow of heavy oil reservoir,the traditional JBN method is not suitable for the determination of oil-water relative permeability curve of heavy oil reservoir using unsteady method.Finally,according to the seepage flow characteristics of heavy oil,this article get a new method to compute the oil-water relative permeability suitable for heavy oil reservoir.This new method can illustrate how the non-linear flow and capillary force effect on relative permeability curve of heavy oil.On the basis of the above research,this paper build a series of forecasting formulas for quantitatively depicting the non-linear flowing law of heavy oil reservoir. |
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